1. Technical Field
The present invention relates to quantum computing, and more particularly to systems and methods for decoupling quantum systems to improve efficiency and reliability of storage of quantum information by dynamical noise suppression techniques.
2. Description of the Related Art
Quantum computers show great promise to far surpass the capabilities of classical computers. However, a major problem with the actual physical realization of a quantum computer is that any quantum system is invariably connected to an environment which causes errors to the computer and, in the worst case, can render the quantum computer useless. Therefore, techniques are needed which a) shield the quantum computer from the environment, b) encode the quantum computer's memory into suitable subspaces by introducing redundancy similar to classical error-correcting codes, and c) provide mechanisms which can be used to suppress noise dynamically by repeatedly applying control operations to the system to drive the system to some stable state.
One major problem is keeping the components of the computer in a coherent state, as the slightest interaction with the external world would cause the system to decohere. This effect causes the unitary character (and more specifically, the invertibility (reversibility)) of quantum computational steps to be violated.
Prior efforts address the problem of dynamical noise suppression using very strong pulses, called hard pulses, which have to be applied to the system at precisely known times. However, pulses with this property are unrealistic from an experimental point of view. There have been efforts to realize dynamical noise suppression with soft pulses; however, such proposed methods do not scale well in terms of a number of pulses that have to be applied to the system.